Complete assignment of the1H and13C NMR spectra of four triterpenes of the ursane, artane, lupane and friedelane groups

The detailed 1H and 13C NMR assignments of the four known triterpenes 3β-hydroxyurs-12-en-28-oic acid, 3-oxo-24-methylenecycloartan, 3-oxo-11α-hydroxy-20(29)lupen and 29-hydroxyfriedelin, isolated from three Brazilian plants, were achieved by 1D and 2D techniques such as DEPT, HETCOR, HMQC, HMBC, COSY and NOESY.